407 lines
9.4 KiB
Java
407 lines
9.4 KiB
Java
// ThreadGroup.java - ThreadGroup class.
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/* Copyright (C) 1998, 1999 Cygnus Solutions
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.lang;
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import java.util.Enumeration;
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import java.util.Vector;
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/**
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* @author Tom Tromey <tromey@cygnus.com>
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* @date August 25, 1998
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*/
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Complete for 1.1. Parts from the JDK 1.0 spec only are
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* not implemented. Parts of the 1.2 spec are also not implemented.
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*/
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public class ThreadGroup
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{
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public int activeCount ()
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{
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int ac = threads.size();
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Enumeration e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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ac += g.activeCount();
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}
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return ac;
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}
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public int activeGroupCount ()
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{
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int ac = groups.size();
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Enumeration e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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ac += g.activeGroupCount();
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}
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return ac;
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}
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// Deprecated in 1.2.
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public boolean allowThreadSuspension (boolean allow)
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{
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// There is no way for a Java program to determine whether this
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// has any effect whatsoever. We don't need it.
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return true;
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}
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public final void checkAccess ()
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{
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SecurityManager s = System.getSecurityManager();
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if (s != null)
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s.checkAccess(this);
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}
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// This is called to remove a ThreadGroup from our internal list.
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private final void remove (ThreadGroup g)
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{
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groups.removeElement(g);
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if (daemon_flag && groups.size() == 0 && threads.size() == 0)
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{
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// We inline destroy to avoid the access check.
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destroyed_flag = true;
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if (parent != null)
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parent.remove(this);
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}
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}
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// This is called by the Thread code to remove a Thread from our
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// internal list. FIXME: currently, it isn't called at all. There
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// doesn't appear to be any way to remove a Thread from a
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// ThreadGroup (except the unimplemented destroy method).
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final void remove (Thread t)
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{
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threads.removeElement(t);
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if (daemon_flag && groups.size() == 0 && threads.size() == 0)
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{
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// We inline destroy to avoid the access check.
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destroyed_flag = true;
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if (parent != null)
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parent.remove(this);
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}
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}
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// This is called by the Thread code to add a Thread to our internal
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// list.
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final void add (Thread t)
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{
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if (destroyed_flag)
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throw new IllegalThreadStateException ();
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threads.addElement(t);
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}
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// This is a helper that is used to implement the destroy method.
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private final boolean canDestroy ()
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{
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if (! threads.isEmpty())
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return false;
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Enumeration e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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if (! g.canDestroy())
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return false;
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}
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return true;
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}
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public final void destroy ()
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{
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checkAccess ();
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if (! canDestroy ())
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throw new IllegalThreadStateException ();
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destroyed_flag = true;
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if (parent != null)
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parent.remove(this);
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}
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// This actually implements enumerate.
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private final int enumerate (Thread[] ts, int next_index, boolean recurse)
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{
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Enumeration e = threads.elements();
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while (e.hasMoreElements() && next_index < ts.length)
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ts[next_index++] = (Thread) e.nextElement();
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if (recurse && next_index != ts.length)
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{
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e = groups.elements();
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while (e.hasMoreElements() && next_index < ts.length)
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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next_index = g.enumerate(ts, next_index, true);
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}
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}
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return next_index;
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}
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public int enumerate (Thread[] ts)
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{
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return enumerate (ts, 0, true);
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}
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public int enumerate (Thread[] ts, boolean recurse)
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{
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return enumerate (ts, 0, recurse);
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}
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// This actually implements enumerate.
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private final int enumerate (ThreadGroup[] ts, int next_index,
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boolean recurse)
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{
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Enumeration e = groups.elements();
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while (e.hasMoreElements() && next_index < ts.length)
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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ts[next_index++] = g;
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if (recurse && next_index != ts.length)
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next_index = g.enumerate(ts, next_index, true);
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}
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return next_index;
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}
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public int enumerate (ThreadGroup[] gs)
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{
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return enumerate (gs, 0, true);
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}
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public int enumerate (ThreadGroup[] gs, boolean recurse)
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{
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return enumerate (gs, 0, recurse);
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}
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public final int getMaxPriority ()
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{
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return maxpri;
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}
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public final String getName ()
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{
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return name;
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}
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public final ThreadGroup getParent ()
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{
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return parent;
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}
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// JDK 1.2.
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// public void interrupt ();
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public final boolean isDaemon ()
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{
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return daemon_flag;
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}
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public synchronized boolean isDestroyed ()
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{
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return destroyed_flag;
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}
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private final void list (String indentation)
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{
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System.out.print(indentation);
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System.out.println(toString ());
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String sub = indentation + " ";
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Enumeration e = threads.elements();
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while (e.hasMoreElements())
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{
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Thread t = (Thread) e.nextElement();
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System.out.print(sub);
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System.out.println(t.toString());
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}
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e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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g.list(sub);
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}
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}
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public void list ()
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{
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list ("");
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}
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public final boolean parentOf (ThreadGroup g)
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{
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while (g != null)
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{
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if (this == g)
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return true;
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g = g.parent;
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}
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return false;
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}
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// Deprecated in 1.2.
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public final void resume ()
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{
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checkAccess ();
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Enumeration e = threads.elements();
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while (e.hasMoreElements())
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{
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Thread t = (Thread) e.nextElement();
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t.resume();
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}
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e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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g.resume();
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}
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}
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public final void setDaemon (boolean daemon)
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{
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checkAccess ();
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daemon_flag = daemon;
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// FIXME: the docs don't say you are supposed to do this. But
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// they don't say you aren't, either.
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if (groups.size() == 0 && threads.size() == 0)
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destroy ();
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}
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public final void setMaxPriority (int pri)
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{
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checkAccess ();
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// FIXME: JDK 1.2 behaviour is different: if the newMaxPriority
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// argument is < MIN_PRIORITY or > MAX_PRIORITY an
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// IllegalArgumentException should be thrown.
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if (pri >= Thread.MIN_PRIORITY && pri <= maxpri)
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{
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maxpri = pri;
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Enumeration e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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g.setMaxPriority (maxpri);
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}
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}
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}
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// Deprecated in 1.2.
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public final void stop ()
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{
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checkAccess ();
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Enumeration e = threads.elements();
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while (e.hasMoreElements())
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{
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Thread t = (Thread) e.nextElement();
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t.stop();
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}
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e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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g.stop();
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}
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}
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// Deprecated in 1.2.
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public final void suspend ()
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{
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checkAccess ();
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Enumeration e = threads.elements();
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while (e.hasMoreElements())
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{
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Thread t = (Thread) e.nextElement();
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t.suspend();
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}
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e = groups.elements();
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while (e.hasMoreElements())
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{
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ThreadGroup g = (ThreadGroup) e.nextElement();
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g.suspend();
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}
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}
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// This constructor appears in the Class Libraries book but in
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// neither the Language Spec nor the 1.2 docs.
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public ThreadGroup ()
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{
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this (Thread.currentThread().getThreadGroup(), null);
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}
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public ThreadGroup (String n)
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{
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this (Thread.currentThread().getThreadGroup(), n);
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}
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public ThreadGroup (ThreadGroup p, String n)
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{
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checkAccess ();
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if (p == null)
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throw new NullPointerException ();
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if (p.destroyed_flag)
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throw new IllegalArgumentException ();
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parent = p;
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name = n;
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maxpri = p.maxpri;
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threads = new Vector ();
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groups = new Vector ();
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daemon_flag = p.daemon_flag;
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destroyed_flag = false;
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p.groups.addElement(this);
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}
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// This is the constructor that is used when creating the very first
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// ThreadGroup. We have an arbitrary argument here just to
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// differentiate this constructor from the others.
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private ThreadGroup (int dummy)
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{
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parent = null;
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name = "main";
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maxpri = Thread.MAX_PRIORITY;
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threads = new Vector ();
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groups = new Vector ();
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daemon_flag = false;
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destroyed_flag = false;
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}
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public String toString ()
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{
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// Language Spec and Class Libraries book disagree a bit here. We
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// follow the Spec, but add "ThreadGroup" per the book. We
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// include "java.lang" based on the list() example in the Class
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// Libraries book.
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return "java.lang.ThreadGroup[name=" + name + ",maxpri=" + maxpri + "]";
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}
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public void uncaughtException (Thread thread, Throwable e)
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{
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// FIXME: in 1.2, this has different semantics. In particular if
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// this group has a parent, the exception is passed upwards and
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// not processed locally.
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if (! (e instanceof ThreadDeath))
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{
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e.printStackTrace();
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}
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}
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// Private data.
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private ThreadGroup parent;
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private String name;
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private int maxpri;
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private Vector threads;
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private Vector groups;
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private boolean daemon_flag;
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private boolean destroyed_flag;
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}
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